Datasheet

Output Port Registers
The output port registers (Table 3) set the outgoing
logic levels of the I/Os defined as outputs by the
respective configuration register. Reads from the output
port registers reflect the value that is in the flip-flop con-
trolling the output selection, not the actual I/O value.
Polarity Inversion Registers
The polarity inversion registers (Table 4) enable polarity
inversion of pins defined as inputs by the respective
port configuration registers. Set the bit in the polarity
inversion register to invert the corresponding port pin’s
polarity. Clear the bit in the polarity inversion register to
retain the corresponding port pin’s original polarity.
Configuration Registers
The configuration registers (Table 5) configure the
directions of the I/O pins. Set the bit in the respective
configuration register to enable the corresponding port
as an input. Clear the bit in the configuration register to
enable the corresponding port as an output.
Standby
The MAX7318 goes into standby when the I
2
C bus is
idle. Standby supply current is typically 5.4µA.
Applications Information
Hot Insertion
The I/O ports I/O0–I/O15, interrupt output INT, and serial
interface SDA, SCL, AD0–2 remain high impedance with
up to 6V asserted on them when the MAX7318 is pow-
ered down (V+ = 0V). The MAX7318 can therefore be
used in hot-swap applications. Note that each I/O’s
100kΩ pullup effectively becomes a 100kΩ pulldown
when the MAX7318 is powered down.
Power-Supply Consideration
The MAX7318 operates from a supply voltage of 2V to
5.5V. Bypass the power supply to GND with a 0.047µF
capacitor as close to the device as possible. For the
QFN version, connect the exposed pad to GND.
MAX7318
2-Wire-Interfaced, 16-Bit, I/O Port Expander
with Interrupt and Hot-Insertion Protection
______________________________________________________________________________________ 11
I7 I6 I5 I4 I3 I2 I1 I0
BIT
I15 I14 I13 I12 I11 I10 I9 I8
Table 2. Registers 0x00, 0x01—Input Port Registers
O7 O6 O5 O4 O3 O2 O1 O0
BIT
O15 O14 O13 O12 O11 O10 O9 O8
Power-up default 1 1111111
Table 3. Registers 0x02, 0x03—Output Port Registers
I/O7 I/O6 I/O5 I/O4 I/O3 I/O2 I/O1 I/O0
BIT
I/O15 I/O14 I/O13 I/O12 I/O11 I/O10 I/O9 I/O8
Power-up default 0 0000000
Table 4. Registers 0x04, 0x05—Polarity Inversion Registers
I/O7 I/O6 I/O5 I/O4 I/O3 I/O2 I/O1 I/O0
BIT
I/O15 I/O14 I/O13 I/O12 I/O11 I/O10 I/O9 I/O8
Power-up default 1 1 1 1 1 1 1 1
Table 5. Registers 0x06, 0x07—Configuration Registers